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Where do you set your timing?
   
   
   
   
   
   
   
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Stock 907 Timing  Rating:  Rating
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 Posted: 03-09-2011 09:18 pm
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SpeedyMitch
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Location: Hailey, Idaho USA
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I've been playing with the timing in my stock '73 and have some observations that others may be able to confirm or deny.

5-degrees before TDC - lumpy idle at about 750 RPM. Some low-end torque but seems flat after about 5k RPM.

10-degrees - idle becomes smooth at about 900 RPM. Less low-end but better response at highway speeds.

15-degrees - high idle (can't seem to bring it down with carbs), no low-end, no better at highway speeds.

Just about everthing I have read says 10 to 15 degrees is 'best' but that has not been my observation.

Note: all observations meticulously measured using my seat-o-the-pants-o-meter.

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 Posted: 03-09-2011 09:44 pm
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subwoofer
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The critical part is the advance at WOT (or vacuum disconnected) and high RPM. It should not be more than 30 degrees, 28 is good. That will bring your idle advance down to ~10 degrees. Unless you change weights and springs, you are stuck with what you get - rev it up and get the high RPM advance right. You will not ruin the engine idling anyway.

The stock JH spec 907 has way too low compression, I run a European 907 from a '78 Lotus Eclat, and 9.5:1 compression and DellOrtos really make a difference.

--
Joachim

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 Posted: 03-10-2011 04:26 am
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Jensen Healey
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Yes, total advance is the limiting factor. I use a MSD6A and minor timing settings make no difference.

Kurt

Don't tell the MGB guys about our advance curve!

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 Posted: 05-28-2011 06:45 am
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StevenD57
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Here is the advance table I am currently running. This is with a standard low compression stock motor.

Attachment: sparktable.png (Downloaded 66 times)

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